AB0901 FUNCTIONAL CAPACITY, BODY COMPOSITION AND DISEASE ACTIVITY ARE ASSOCIATED WITH QUALITY OF LIFE IN PATIENTS WITH MYOSITIS
Authors: K. Y. Jensen, P. Aagaard, C. Suetta, J. Nielsen, H. D. Schrøder, C. Grønset, L. P. Diederichsen
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Idiopathic inflammatory myopathies – or briefly myositis – has cardinal traits of muscle weakness <sup>[1]</sup> and decreased muscle endurance <sup>[2]</sup> in addition to reduced quality of life (QoL) <sup>[3]</sup>. However, QoL is complex, and it is unclear which factors affect QoL in patients with myositis. Knowledge of these factors and potential associations to QoL is of importance for evoking changes to a better life for patients with myositis. <h3>Objectives</h3> To investigate the influence of functional capacity, muscle strength, body composition and disease activity and damage on QoL in patients with myositis. <h3>Methods</h3> Measures of functional capacity (functional index 3, 2-minute walk test, timed-up-and- go and 30-s sit-to-stand), muscle strength (5 repetitions maximum strength in leg press, bench press, cable row, knee extension, biceps curl and static handgrip strength; all expressed relative to body mass), leg extensor power (Nottingham Power Rig, relative to body mass), body composition (height adjusted appendicular lean mass and fat mass) and IMACS (International Myositis Assessment &amp; Clinical Studies Group) disease activity and disease damage core set measures were analysed to investigate the impact on QoL (physical- and mental component summary in the Short Form 36 questionnaire (SF-36)). <h3>Results</h3> All functional capacity measures were positively correlated with the physical component summary (PCS); functional index 3 (r<sup>2</sup>=0.15, p=0.03), 2-minute walk test (r<sup>2</sup>=0.26, p=0.003), timed-up-and-go (r<sup>2</sup>=0.14, p=0.03) and 30-sit-to-stand performance (r<sup>2</sup>=0.15, p=0.03). Only leg press (r<sup>2</sup>=0.15, p=0.04) showed a positive correlation with PCS for measures of muscle strength and power. For body composition, height-adjusted fat mass correlated negatively with PCS (r<sup>2</sup>=0.20, p=0.01). Of the IMACS disease activity and disease damage core set measures, Health Assessment Questionnaire (r<sup>2</sup>=0.40, p=0.0001), Physician Global Assessment of Disease Damage (r<sup>2</sup>=0.44, p&lt;0.001) and Patient Global Assessment of Disease Damage (r<sup>2</sup>=0.18, p=0.02) were negatively correlated with PCS. In contrast, none of the investigated outcome parameters were correlated with the mental component summary of SF-36. <h3>Conclusion</h3> In the present group of patients with myositis, functional capacity and muscle strength had positive associations with the physical component summary of the QoL, indicating that future interventions should be directed to improve these factors to ultimately improve QoL. The Health Assessment Questionnaire and Patient/Physician Global Assessment of Disease Damage revealed strong correlations with PCS, supporting that both patient-reported outcome measures (PROMS) and clinician-reported outcomes are highly relevant QoL-related monitoring parameters in patients with myositis. <h3>References</h3> [1]Amato AA, Greenberg SA. Inflammatory myopathies. <i>Continuum (Minneap Minn</i>). 2013;19(6 Muscle Disease):1615-1633. doi:10.1212/01.CON.0000440662.26427.bd [2]Alemo Munters L, Dastmalchi M, Katz A, et al. Improved exercise performance and increased aerobic capacity after endurance training of patients with stable polymyositis and dermatomyositis. <i>Arthritis Res Ther</i>. 2013;15(4):R83. Published 2013 Aug 13. doi:10.1186/ar4263 [3]Poulsen KB, Alexanderson H, Dalgård C, Jacobsen S, Weile L, Diederichsen LP. Quality of life correlates with muscle strength in patients with dermato- or polymyositis. <i>Clin Rheumatol</i>. 2017;36(10):2289-2295. doi:10.1007/s10067-017-3706-6 <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Kasper Yde Jensen: None declared, Per Aagaard: None declared, Charlotte Suetta: None declared, Jakob Nielsen: None declared, Henrik Daa Schrøder: None declared, Charlotte Grønset: None declared, Louise Pyndt Diederichsen Speakers bureau: Boehringer Ingelheim, Grant/research support from: Boehringer Ingelheim.